Sailing Kayak DIY Project

[DrConny]

Hello everybody at the forum.

I am starting shorty a project transforming my sit-on-top kayak to a sailing kayak.
Some info about the Kayak first
Its a PVP sit-on-top Kayak
Dimensions :
Length: 249 cm (6.56 feet)
Width : 71 cm (2.49 feet)
Height: 41 cm (1.34 feet) at the bow (front)
35 cm (1.14 feet) at the tail (rear)

The Mast will be on sitting on a metal and wood base that will be fixed on the kayak body using belts (transportation type belts see attached picture).
I do now want to drill or plastic-weld anything on the Kayak in fear of damaging it.
The base is designed with a help of an engineer friend. (I dont have the designs yet).

My biggest concern is the position of the Mast and the centerboard.
On the attached design you can see where the mast and centerboard are able to be placed according to the existing shape of the kayak( I dont have much choice there I think).
I was wondering if somebody with more experience can offer any comments on the location/placement of the centerboard and sail as well as the size of both.
With the prelimilary design the sail should be about 0.84 sq. meter (9 sq. foot) and it looks small to me...

The rudder will be steerable and retractable and hopefull the centerbopard will be also detachable (for easy of storing).

I have attached also some pics of the kayak for reference.

Any commentary will be greatly appreciated!!!

 

[hoytedow]

Welcome, DrConny.
You might want to look at some pictures of successful kayak rigs and adjust accordingly.

The rig shown below took part in the Everglades Challenge, an event which departed Mullet Key in Central Florida and finished at Key Largo.

 

[DrConny]

Thank for the reply!

Please excuse my english and lack of knowledge of the nautical terms in english but my first language is Greek.

I have already checked the kayaksailor.com rig and various similar rigs.
In the installations I have checked I cant see if they have a centerboard underneath their kayaks.
Also I am thinking of copying this sail shape but then I cant fix a line from the top of the mast to the rear.
Do you think the rudder and the existing keel of the kayak would be enough for stabilising ?

 

[hoytedow]

I think you would need floats to keep the boat stable.

 

[messabout]

DrConny; I will try to explain about the general idea for sail and centerboard placement. This will be a generalization, merely a starting point. You will need to make minor adjustments as you experiment with the locations.

The sail has a certain location on its fabric where the force of the wind is concentrated. That is called the center of effort. (CE). For the sake of simplicity just find the geometric center of the sail. That is not a technically pefect way to do it but let us keep this simple.

Consider that the wind exerts a pressure on the sail. The sail will tend to push the boat forward but it will have a large tendency to push the boat sideways at the same time. You must have some counteracting device that will minimze the sideways movement. That would be the center board. The board will have a location called the center of lateral area (CLA). For simplicity, just use the geometric center of the underwater part of the board.

Now you have identified the location of the CE and the CLA. Arrange the sail and the board so that the CLA is slightly ahead of the CE by a few centimeters. That will get you somewhere near the most advantageous positions. You may have to move the mast a few cm foreward or aft to get the best relative locations. Finding the right location is purely an experimental process. In this case it will be easy because you will be using straps to hold the mast base in position. If the board is too far ahead of the CE, the boat will try to turn itself into the wind. That is called weather helm. If the board is too far behind the CE the boat will try to turn itself away from the wind direction which is called lee helm. Excessive lee helm will render the boat uncontrollable. Excessive weather helm will tend to stall the boat because you will have to pull on the tiller handle very hard and the rudder will be turned too much.

Your tiny kayak is not going to sail very well no matter what you do. The top speed will not be more than a casual walking speed. The boat will not be able to tolerate much sail area because the boat is narrow and small. Perhaps if you used outriggers as Hoyt has suggested, you could use as much as 3 square meters of sail. WIthout the outriggers you will be fortunate to carry half that much sail and then only if you are very athletic.

I hope that this is sufficiently helpful.

 

[sharpii2]

Here's an idea I had, a while back.

The floats shown here (see attachment) are not full buoyancy and can be pushed under, making the rig relatively hard to capsize.

The cross beam structure, along with the floats, take most of the sailing loads.

Except for steering, the hull is pretty much being towed.

The floats have a keel on each, which is the only part of them that will immersed when the kayak is level. This, hopefully, will make for easier paddling, if the wind quits.

The rig is strapped onto the hull, so no holes need to be drilled.

The rudder attachment might be a bit of a problem. Perhaps a rudder can be added to each float.

 

[Petros]

Welcome to the list Dr. Conny, your English is fine.

I would move both the sail and the dagger board further forward, as drawn the sail would be right in your lap. Keep the sail small, one squre meter or less, and match the areas as Messabout explains, you should be fine. The keel/daggar board area should be about 5 percent of sail area for a small boat, and the rudder about half that.

A longer hull would be much better, conventional seakayak is about 17 ft (5.2 meters) and would make a better sailboat if you put out riggers to make it a trimiran. It would take more sail and be much faster.

Your current sit-on-top would work okay with a small sail. It small size makes it slow and difficult to control if you put more than a small sail on it. It can be done, keep is simple and small and you can go have fun with it. Once you get bored than you can move on to a larger sailboat.

My mother was born in Athens BTW, I have been to the mainland and some of the Greek islands, but never made it to Santorini. Someday I would like to take my wife and family to the area to spend a summer sailing the Greek islands.

 

[paddilack]

Flat Earth

Hello.
My take on this is that for kayak sailing with a small rig it is not necessary to have a centerboard/ leeboard.
It may help, but it is possible to enjoy sailing without one.

I have a 17 feet sea kayak with a Flat Earth Kayaksail of .8 sqare meters, and have sailed for a season both with and without leeboard. I have not tried outriggers, and do not see the need in moderate condititons.

I have paddled for several decades, but have no previous experience sailing, and just learned from this tread that I have placed the leeboard way too far back. (at least 1,5 meters from the mast) This may well be why I havent been able to notice much benefit from it. Some more experimentation this year

I learned a lot from the blog Gnarlydognews who has done a lot of sailing with this type of rig. (no leeboards or outriggers)

Such a small sail gives a meaningful assist in both speed and range, but I find myself paddeling as well with the sail up. Wich is how I like it. Just sailing gets a little, Well, not boring, but passive I suppose.
Top speed noted on gps so far is 13km/h wich is roughly twice my sprint speed with paddle alone.

So far so good as they say.

Best of luck, and keep experimenting safely

Regards Padillac

 

[westkyle]

I've decided not to make my own post since the information may help the OP as well. I have a 10ft long, 2ft 5in wide, 1ft tall(at the widest point of course) kayak. I want to build some amas for it and make or buy a mast for sailing in a lake/wide slow moving river. Here are some questions I have thought of. I'll get pictures of it asap so better information can be provided.

How do I know where to place the mast? What material should the mast be made out of? What should I make a mast step out of that would handle maybe 10-15mph winds(maybe more than that if I am adventurous)?

What should the dimensions of the amas be? Are they supposed to be slightly out of the water? How far out should the amas be in relation to the kayak?

What should the size and shape of the sail be? What should the sail be made out of?

Also, what about a leeboard? Will I need one? I could install a retractable centerboard, but it seems like to much of a bad idea to fiberglass one in on this kayak.

 

[paddilack]

You can check out solwaydory.co.uk and karitek.co.uk for general ideas and also kits of different kinds. There are many others of course, but I at least found much information on their sites. Good luck and fair winds

 

[westkyle]

Here are some pictures. Any other information you guys can provide would be helpful. Added them as attachments. I want to make it into a trimaran.

 

[paddilack]

From your description I would look hard at Sharpii2s idea a few posts above.
put the maststep on the base for the akas, and position the hole package far enough to the front so it doesent interfere with paddeling.
When experimenting with placement I strap the whole contraption to the hull with adjustable loading straps around the hull. This creates a bit of water resistance, but has the benefit of not making any permanent changes to your boat until you are satisfied with your results.

Best of luck!
Padillac

 

[falconsails]

I have arrived late at this discussion, bout would like to suggest you try a Falcon Sail.
I am the maker of Falcon Sails, and we provide rigging for every kind of kayak.
The rigs weigh 4 pounds total, and provide maximum propulsion per square inch.
You can sail up wind without a center board or lee board. I sail within 60 degrees of straight up wind without thinking about it. If I concentrate and paddle as I sail, I can get useful propulsion to within 30 degrees of straight up wind.

I could go on and on.

Here is my website on kayak sailing http://www.falconsails.com

Here are my personal kayak sailing pictures.
http://www.flickr.com/photos/30659399@N02/

Here is one of my favorite videos.
https://www.youtube.com/watch?v=ysVTtX4H8B0
You can see the performance of these rigs are impressive and way beyond what anybody would expect out of a kayak sail.

Here is another good video.
https://www.youtube.com/watch?v=wzj2RBy80zc

Have a great paddle sail.

Patrick Forrester
Falcon Sails LLC